Sometimes it's useful to dissect a policy debate with lots of figures, quotes from experts, careful scrutiny of history, etc. And sometimes it's useful just to take a step back and describe the two sides in simple, basic terms. Here's an excellent attempt at the second method, by the Atlantic's Derek Thompson:
One side doesn't want to spend more money to insure more Americans, and the other side wants to pay for their insurance with tax increases and spending cuts. The numbers are beside the point now. This isn't a math problem, and it's not even really a debate anymore, it's a calcified difference of ideology.